Solid feed guide apparatus for a solid feed pump

ABSTRACT

In one embodiment, a system includes a solid feed pump. The solid feed pump includes a housing, a rotor disposed in the housing, a curved passage disposed between the rotor and the housing, an inlet port coupled to the curved passage, an outlet port coupled to the curved passage, a solid feed guide extending across the curved passage, and multiple discrete contacts distributed along an interface between the solid feed guide and the rotor.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to a pump for a solid, such as particulate matter.

A typical pump designed for solids, such as particulate matter, has a single continuous channel. For example, the pump may be a rotary pump that drives the solids along a circular path. Thus, the rotary pump has stationary and rotating components that interface with one another. Unfortunately, the flow of solids at the inlet and outlet of the pump may cause high stresses and friction between the stationary and rotating components of the pump, thereby causing high heat generation in the pump.

BRIEF DESCRIPTION OF THE INVENTION

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

In a first embodiment, a system includes a solid fuel pump. The solid fuel pump includes a housing, a rotor disposed in the housing; a curved passage disposed between the rotor and the housing, an inlet port coupled to the curved passage, an outlet port coupled to the curved passage, a solid fuel guide extending across the curved passage, and a first roller at an interface between the solid fuel guide and the rotor.

In a second embodiment, a system includes a solid feed pump. The solid feed pump includes a housing, a rotor disposed in the housing, a curved passage disposed between the rotor and the housing, an inlet port coupled to the curved passage, an outlet port coupled to the curved passage, a solid feed guide extending across the curved passage, and multiple discrete contacts distributed along an interface between the solid feed guide and the rotor.

In a third embodiment, a system includes a solid feed pump. The solid feed pump includes a housing, a rotor disposed in the housing, a curved passage disposed between the rotor and the housing, an inlet port coupled to the curved passage, an outlet port coupled to the curved passage, a solid feed guide extending across the curved passage, and a discrete static contact at an interface between the solid feed guide and the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic block diagram of an embodiment of an integrated gasification combined cycle (IGCC) power plant utilizing a solid feed pump;

FIG. 2 is a cross-sectional side view of an embodiment of a solid feed pump;

FIG. 3 is a cross-sectional side view of an embodiment of a solid feed guide;

FIG. 4 is a cross-sectional side view of another embodiment of a solid feed guide;

FIG. 5 is a cross-sectional side view of an embodiment of a bearing, as shown in FIG. 3, disposed in a recess of the solid feed guide;

FIG. 6 is a face view of an embodiment of a solid feed guide, taken along line 6-6 of FIG. 3;

FIG. 7 is a face view of an embodiment of a solid feed guide, taken along line 6-6 of FIG. 3;

FIG. 8 is a perspective view of an embodiment of a solid feed guide;

FIG. 9 is a side view of a solid feed guide with a movable discrete contact located behind the solid feed guide; and

FIG. 10 is a cross-sectional side view of a solid feed guide with a plurality of adjustable movable discrete contacts.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Embodiments of the present disclosure include a solid feed pump with a solid feed guide at an inlet and/or outlet, wherein the solid feed guide includes unique features to increase support, reduce friction, reduce stresses, and reduce heat generation at an interface between the solid feed guide and a rotor. As discussed in detail below, the unique features may include one or more static or movable contacts at the interface between the solid feed guide and the rotor. For example, the contacts may include curved protrusions, such as semi-spherical, cylindrical, or convex protrusions, at discrete points between the solid feed guide and the rotor. By further example, the contacts may include rollers, such as cylindrical or spherical rollers. In certain embodiments, the contacts are disposed directly between the solid feed guide and the rotor, whereas other embodiments position the contacts at an offset from the interface. In each of the disclosed embodiments, the contacts reduce friction, wear, heat generation, and stresses at the interface.

FIG. 1 is a diagram of an embodiment of an integrated gasification combined cycle (IGCC) system 100 utilizing one or more solid feed pumps 10 with unique features at a rotating interface as mentioned above. The solid feed pump 10 may be a posimetric pump. The term “posimetric” may be defined as capable of metering (e.g., measuring an amount of) and positively displacing (e.g., trapping and forcing displacement of) a substance being delivered by the pump 10. The pump 10 is able to meter and positively displace a defined volume of a substance, such as a solid fuel feedstock. The pump path may have a circular shape or curved shape. Although the solid feed pump 10 is discussed with reference to the IGCC system 100 in FIG. 1, the disclosed embodiments of the solid feed pump 10 may be used in any suitable application (e.g., production of chemicals, fertilizers, substitute natural gas, transportation fuels, or hydrogen). In other words, the following discussion of the IGCC system 100 is not intended to limit the disclosed embodiments to IGCC.

The IGCC system 100 produces and burns a synthetic gas, i.e., syngas, to generate electricity. Elements of the IGCC system 100 may include a fuel source 102, such as a solid feed, that may be utilized as a source of energy for the IGCC. The fuel source 102 may include coal, petroleum coke, biomass, wood-based materials, agricultural wastes, tars, asphalt, or other carbon containing items. The solid fuel of the fuel source 102 may be passed to a feedstock preparation unit 104. The feedstock preparation unit 104 may, for example, resize or reshape the fuel source 102 by chopping, milling, shredding, pulverizing, briquetting, or palletizing the fuel source 102 to generate a dry feedstock (e.g., particulate matter).

In the illustrated embodiment, the solid feed pump 10 delivers the feedstock from the feedstock preparation unit 104 to a gasifier 106. The solid feed pump 10 may be configured to meter and pressurize the fuel source 102 received from the feedstock preparation unit 104. The gasifier 106 may convert the feedstock into a syngas, e.g., a combination of carbon monoxide and hydrogen. This conversion may be accomplished by subjecting the feedstock to a controlled amount of steam and oxygen at elevated pressures, e.g., from approximately 20 bar to 85 bar, and temperatures, e.g., approximately 700 degrees Celsius to 1600 degrees Celsius, depending on the type of gasifier 106 utilized.

The gasification process may include the feedstock undergoing a pyrolysis process, whereby the feedstock is heated. Temperatures inside the gasifier 106 may vary during the pyrolysis process, depending on the fuel source 102 utilized to generate the feedstock. The heating of the feedstock during the pyrolysis process may generate a solid, (e.g., char), and residue gases, (e.g., carbon monoxide, hydrogen, and nitrogen). The char remaining from the feedstock from the pyrolysis process may only weigh up to approximately 30% of the weight of the original feedstock.

A partial oxidation process may then occur in the gasifier 106. The combustion may include introducing oxygen to the char and residue gases. The char and residue gases may react with the oxygen to form carbon dioxide and carbon monoxide, which provides heat for the gasification reactions. The temperatures during the partial oxidation process may range from approximately 700 degrees Celsius to 1600 degrees Celsius. Steam may be introduced into the gasifier 106 during gasification. The char may react with the carbon dioxide and steam to produce carbon monoxide and hydrogen at temperatures ranging from approximately 800 degrees Celsius to 1100 degrees Celsius. In essence, the gasifier utilizes steam and oxygen to allow some of the feedstock to be “burned” to produce carbon monoxide and release energy, which drives a second reaction that converts further feedstock to hydrogen and additional carbon dioxide.

In this way, a resultant gas is manufactured by the gasifier 106. This resultant gas may include approximately 85% of carbon monoxide and hydrogen in equal proportions, as well as CH₄, HCl, HF, COS, NH₃, HCN, and H₂S (based on the sulfur content of the feedstock). This resultant gas may be termed untreated, raw, or sour syngas, since it contains, for example, H₂S. The gasifier 106 may also generate waste, such as slag 108, which may be a wet ash material. This slag 108 may be removed from the gasifier 106 and disposed of, for example, as road base or as another building material. Prior to cleaning the raw syngas, a syngas cooler 107 may be utilized to cool the hot syngas. The cooling of the syngas may generate high pressure steam which may be utilized to produce electrical power as described below. After cooling the raw syngas, a gas cleaning unit 110 may be utilized to clean the raw syngas. The gas cleaning unit 110 may scrub the raw syngas to remove the HCl, HF, COS, HCN, and H₂S from the raw syngas, which may include separation of sulfur 111 in a sulfur processor 112 by, for example, an acid gas removal process in the sulfur processor 112. Furthermore, the gas cleaning unit 110 may separate salts 113 from the raw syngas via a water treatment unit 114 that may utilize water purification techniques to generate usable salts 113 from the raw syngas. Subsequently, the gas from the gas cleaning unit 110 may include treated, sweetened, and/or purified syngas, (e.g., the sulfur 111 has been removed from the syngas), with trace amounts of other chemicals, e.g., NH₃ (ammonia) and CH₄ (methane).

A gas processor 116 may be utilized to remove residual gas components 117 from the treated syngas such as, ammonia and methane, as well as methanol or any residual chemicals. However, removal of residual gas components 117 from the treated syngas is optional, since the treated syngas may be utilized as a fuel even when containing the residual gas components 117, e.g., tail gas. At this point, the treated syngas may include approximately 3% CO, approximately 55% H₂, and approximately 40% CO₂ and is substantially stripped of H₂S. This treated syngas may be transmitted to a combustor 120, e.g., a combustion chamber, of a gas turbine engine 118 as combustible fuel. Alternatively, the CO₂ may be removed from the treated syngas prior to transmission to the gas turbine engine.

The IGCC system 100 may further include an air separation unit (ASU) 122. The ASU 122 may operate to separate air into component gases by, for example, distillation techniques. The ASU 122 may separate oxygen from the air supplied to it from a supplemental air compressor 123, and the ASU 122 may transfer the separated oxygen to the gasifier 106. Additionally the ASU 122 may transmit separated nitrogen to a diluent nitrogen (DGAN) compressor 124.

The DGAN compressor 124 may compress the nitrogen received from the ASU 122 at least to pressure levels equal to those in the combustor 120, so as not to interfere with the proper combustion of the syngas. Thus, once the DGAN compressor 124 has adequately compressed the nitrogen to a proper level, the DGAN compressor 124 may transmit the compressed nitrogen to the combustor 120 of the gas turbine engine 118. The nitrogen may be used as a diluent to facilitate control of emissions, for example.

As described previously, the compressed nitrogen may be transmitted from the DGAN compressor 124 to the combustor 120 of the gas turbine engine 118. The gas turbine engine 118 may include a turbine 130, a drive shaft 131 and a compressor 132, as well as the combustor 120. The combustor 120 may receive fuel, such as syngas, which may be injected under pressure from fuel nozzles. This fuel may be mixed with compressed air as well as compressed nitrogen from the DGAN compressor 124, and combusted within combustor 120. This combustion may create hot pressurized exhaust gases.

The combustor 120 may direct the exhaust gases towards an exhaust outlet of the turbine 130. As the exhaust gases from the combustor 120 pass through the turbine 130, the exhaust gases force turbine blades in the turbine 130 to rotate the drive shaft 131 along an axis of the gas turbine engine 118. As illustrated, the drive shaft 131 is connected to various components of the gas turbine engine 118, including the compressor 132.

The drive shaft 131 may connect the turbine 130 to the compressor 132 to form a rotor. The compressor 132 may include blades coupled to the drive shaft 131. Thus, rotation of turbine blades in the turbine 130 may cause the drive shaft 131 connecting the turbine 130 to the compressor 132 to rotate blades within the compressor 132. This rotation of blades in the compressor 132 causes the compressor 132 to compress air received via an air intake in the compressor 132. The compressed air may then be fed to the combustor 120 and mixed with fuel and compressed nitrogen to allow for higher efficiency combustion. Drive shaft 131 may also be connected to load 134, which may be a stationary load, such as an electrical generator for producing electrical power, for example, in a power plant. Indeed, load 134 may be any suitable device that is powered by the rotational output of the gas turbine engine 118.

The IGCC system 100 also may include a steam turbine engine 136 and a heat recovery steam generation (HRSG) system 138. The steam turbine engine 136 may drive a second load 140. The second load 140 may also be an electrical generator for generating electrical power. However, both the first and second loads 134, 140 may be other types of loads capable of being driven by the gas turbine engine 118 and steam turbine engine 136. In addition, although the gas turbine engine 118 and steam turbine engine 136 may drive separate loads 134 and 140, as shown in the illustrated embodiment, the gas turbine engine 118 and steam turbine engine 136 may also be utilized in tandem to drive a single load via a single shaft. The specific configuration of the steam turbine engine 136, as well as the gas turbine engine 118, may be implementation-specific and may include any combination of sections.

The IGCC system 100 may also include the HRSG 138. High pressure steam may be transported into the HSRG 138 from the syngas cooler 107. Also, heated exhaust gas from the gas turbine engine 118 may be transported into the HRSG 138 and used to heat water and produce steam used to power the steam turbine engine 136. Exhaust from, for example, a low-pressure section of the steam turbine engine 136 may be directed into a condenser 142. The condenser 142 may utilize a cooling tower 128 to exchange heated water for chilled water. The cooling tower 128 acts to provide cool water to the condenser 142 to aid in condensing the steam transmitted to the condenser 142 from the steam turbine engine 136. Condensate from the condenser 142 may, in turn, be directed into the HRSG 138. Again, exhaust from the gas turbine engine 118 may also be directed into the HRSG 138 to heat the water from the condenser 142 and produce steam.

In combined cycle systems such as IGCC system 100, hot exhaust may flow from the gas turbine engine 118 and pass to the HRSG 138, along with the steam generated by the syngas cooler 107, where it may be used to generate high-pressure, high-temperature steam. The steam produced by the HRSG 138 may then be passed through the steam turbine engine 136 for power generation. In addition, the produced steam may also be supplied to any other processes where steam may be used, such as to the gasifier 106. The gas turbine engine 118 generation cycle is often referred to as the “topping cycle,” whereas the steam turbine engine 136 generation cycle is often referred to as the “bottoming cycle.” By combining these two cycles as illustrated in FIG. 1, the IGCC system 100 may lead to greater efficiencies in both cycles. In particular, exhaust heat from the topping cycle may be captured and used to generate steam for use in the bottoming cycle.

As mentioned above, the IGCC system 100 may include one or more solid feed pumps 10. FIG. 2 is a cross-sectional side view of an embodiment of the solid feed pump 10, further illustrating operational features of the solid feed pump 10. As shown in FIG. 2, the solid feed pump 10 includes a housing 214, inlet 200, outlet 202, and rotor 204. The rotor 204 may include two substantially opposed and parallel rotary discs 206 and 208, which include discrete cavities defined by protrusions to drive solids there between. The rotary discs 206 and 208 may be movable relative to the housing 214 in a rotational direction 216 from the inlet 200 towards the outlet 202. The inlet 200 and the outlet 202 may be coupled to a curved passage 210 (e.g., circular or annular passage). A curved passage 210 may be disposed between the two rotary discs 206 and 208 and within the housing 214. A solid feed guide 212 may be disposed adjacent the outlet 202. In some embodiments, the solid feed guide 212 may be disposed adjacent the inlet 200 or at both the inlet 200 and the outlet 202. The solid feed guide 212 may extend across the curved passage between rotary discs 206 and 208. The solid feed guide 212 may include an upper portion 218 and a lower portion 220. The lower portion 220 of the solid feed guide 212 may include a guide wall 222 and a surface 224 that interfaces with the rotor 204. To ensure efficient performance of the solid feed pump 10, the rotor interfacing surface 224 of the solid feed guide 212 may be tightly contoured to the shape of an outer surface 226 of the rotor 204. Together the guide wall 222 and the rotor interfacing surface 224 may form a tip 228 at the lower portion 220 of the solid feed guide 212. The rotor interfacing surface 224 near the tip 228 may contact the rotor surface 204 while the rest of the rotor interfacing surface 224 may include a slight gap between the rotor interfacing surface 224 and the rotor surface 204 that gradually increases from the tip 228 towards the opposite end of the rotor interfacing surface 224. The outlet 202, or in some embodiments the inlet 200, may provide a fixed support to the upper portion 218 of the solid feed guide 212. As discussed in detail below, the discussed embodiments include one or more discrete contacts between the surfaces 224 and 226, thereby reducing friction, heat generation, and stresses.

As particulate matter is fed through an opening 230 of the inlet 200, the solid feed pump 10 may impart a tangential force or thrust to the particulate matter in the rotational direction 216 of the rotor 204. The direction of flow 234 of the particulate matter is from the inlet 200 to the outlet 202. As the particulate matter rotates through the curved passage 210, the particulate matter encounters the guide wall 222 of the solid feed guide 212 disposed adjacent the outlet 202 extending across the curved passage 210. The particulate matter is diverted by the solid feed guide 212 through an opening 236 of the outlet 202 into an exit pipe 238 connected to a high pressure vessel or into a conveyance pipe line.

The guide wall 222 may substantially block the curved passage 210. In some embodiments, the guide wall 222 may only partially block the curved passage 210. The guide wall 222 extends radially outward from the rotor 204. The guide wall 222 may be angled in a radial direction relative to the rotor 204. For example, the radial angle (i.e., angle between guide wall 222 and the rotor 204) may range between approximately 0 to 90 degrees, 0 to 60 degrees, 30 to 60 degrees, 0 to 45 degrees, 30 to 45 degrees, 0 to 30 degrees, or 0 to 15 degrees, or any angle therebetween. By further example, the radial angle may be approximately 30, 35, 40, 45, 50, 55, or 60 degrees, or any angle therebetween.

The impact of the particulate matter on the solid feed guide 212 may create a load pressure on the guide wall 222. The load pressure may increase the sliding friction between the rotor interfacing surface 224 and the outer surface 226 of the rotor 204. The increase in friction may result in an increase in heat generation at the rotor interfacing surface 224 near the tip 228 of the solid feed guide 212. Besides increasing friction, the load pressure created by the particulate matter on the solid feed guide 212 may increase the high stresses experienced by the solid feed guide 212, particularly at the tip 228. Together, the high heat generation and the high stresses may accelerate the rate of tip wear. However, as discussed below, the disclosed embodiments include one or more discrete contacts at the surfaces 224 and 226 to reduce friction, heat generation, and stresses.

FIGS. 3-10 illustrate embodiments of the solid feed guide 212 with unique contacts that may reduce the heat generation and stresses experienced by the solid feed guide 212. The contacts discussed below are disposed on the surface 224 of the solid feed guide 212. FIG. 3 illustrates a cross-sectional side view of an embodiment of the solid feed guide 212. As mentioned above, the solid feed guide 212 may include upper portion 218 and lower portion 220. The lower portion 220 of the solid feed guide 212 may include the guide wall 222, rotor interfacing surface 224, and tip 228. In addition, the lower portion 220 may include multiple discrete contacts 250 distributed along the rotor interfacing surface 224. Each of the multiple discrete contacts 250 may present a curved or arcuate surface when interfacing with the outer surface 226 of the rotor 204. The extent to which the multiple discrete contacts 250 extend out from the rotor interfacing surface 224 may vary. The size and shape of the multiple discrete contacts 250 also may vary. For example, the contacts 250 may be spherical, cylindrical, or any suitable curved shape. The multiple discrete contacts 250 may be arranged in a pattern or randomly distributed on the rotor interfacing surface 224.

The illustrated multiple discrete contacts 250 are movable. For example, the multiple discrete contacts 250 may roll in the rotational direction 216 of the rotor 204. In addition, the multiple discrete contacts 250 may be made of a low-friction material and have a rolling friction coefficient less than the sliding friction coefficient experienced by the rotor interfacing surface 224 in the absence of the multiple discrete contacts 250. For example, the low-friction material may include high alloy steel, stainless steel, chrome steel, ceramic, plastic, or a combination thereof. Thus, the multiple discrete contacts 250 may generate less heat and may reduce the total heat generated between the solid feed guide 212 and the rotor 204. Besides reducing friction, the multiple discrete contacts 250 may provide extra support to the lower portion 220 of the solid feed guide 212, particularly the rotor interfacing surface 224. As a result of this additional support, the high stresses experienced by the lower portion 220 of the solid feed guide 212 may be reduced, particularly the stresses near the tip 228. Other embodiments may include both movable and static discrete contacts 250.

In some embodiments, the multiple discrete contacts 250 may be stationary. FIG. 4 illustrates a cross-sectional side view of another embodiment of the solid feed guide 212. Similar to FIG. 3, the solid feed guide 212 includes the upper portion 218 and the lower portion 220 that may include guide wall 222, the rotor interfacing surface 224, and the tip 228. The rotor interfacing surface 224 also may include multiple discrete contacts 250. The multiple discrete contacts 250 illustrated are static discrete contacts 260. As illustrated, the static discrete contacts 260 are integral to the solid feed guide 212 and may be made of a low-friction material. For example, the low-friction material may include high alloy steel, stainless steel, chrome steel, ceramic, plastic, or a combination thereof. Alternatively, the static discrete contacts 260 may be affixed to the rotor interfacing surface 224. If the static discrete contacts 260 are affixed to the solid feed guide 212, then the static discrete contacts 260 may be made of the same constituent material as the solid feed guide 212. In other embodiments, the affixed static discrete contacts 260 may be made of a low-friction material different from the constituent material of the solid feed guide 212. Each of the static discrete contacts 260 may present a curved or arcuate surface when interfacing with the outer surface 226 of the rotor 204. The extent to which the static discrete contacts 260 extend out from the rotor interfacing surface 224 may vary. The size and shape of the static discrete contacts 260 may also vary. For example, the contacts 260 may be semi-spherical, convex, partial cylindrical, disc-shaped, or any other curved protruding shape. The static discrete contacts 260 may be arranged in a pattern or randomly distributed on the rotor interfacing surface 224. Also, similar to the discrete contacts 250 embodied in FIG. 3, the static discrete contacts 260 may similarly reduce the high stresses experienced by the lower portion 220 of the solid feed guide 212, particularly the tip 228.

As mentioned above in FIG. 3, the multiple discrete contacts 250 may be movable. FIG. 5 illustrates a cross-sectional side view of an embodiment of a bearing 270, as shown within line 5-5 of FIG. 3, of the solid feed guide 212. The illustrated embodiment shows a portion of the rotor interfacing surface 224 of the solid feed guide 212 and the bearing 270 disposed in a recess 272 of the rotor interfacing surface 224. The recess 272 may be concave in order to allow the bearing 270 to rotate within the recess 272 when the bearing 270 rotates in a direction opposite the rotational direction 216 of the rotor 204. The dimensions of the recess 272 may vary with the size of the bearing 270. The bearing 270 may be spring loaded into the recess 272 or captured between the surfaces 224 and 226. The bearing 270 may be made of a low-friction material with a rolling friction coefficient less than the sliding friction coefficient of the rotor interfacing surface 224 in the absence of the bearing 270. For example, the low-friction material may include high alloy steel, stainless steel, chrome steel, ceramic, plastic, or a combination thereof.

FIG. 6 is a partial face view of an embodiment of a solid feed guide 212, taken along line 6-6 of FIG. 3, illustrating cylindrical shapes of the bearings 270. The illustrated embodiment shows multiple cylindrical bearings 280 disposed along the rotor interfacing surface 224 of the solid feed guide 212. The rotor interfacing surface 224 may include a top portion 282 and a lower portion 284. The lower portion 284 is nearest the tip 228. As mentioned above, the cylindrical bearings 280 may be spring loaded into the concave recess 272 or captured between the surfaces 224 and 226. The cylindrical bearings 280 may be disposed along the entire width 286 of the rotor interfacing surface 224, or less than the entire width 286. The length 288 and diameter 290 of each cylindrical bearing 280 may be uniform or non-uniform. Likewise, the length 288 and diameter 290 may be the same or different from one bearing 280 to another. In some embodiments, the multiple cylindrical bearings 280 may occupy the same longitudinal axis. In other words, each illustrated bearing 280 may be segmented into multiple cylindrical bearings across the width 286. Furthermore, spacing 292 between cylindrical bearings 280 may be constant or vary.

Alternatively, the bearings 270 may include ball bearings 300. FIG. 7 illustrates a partial face view of an embodiment of solid feed guide 212, along the rotor interfacing surface 224, as indicated by line 6-6 of FIG. 3. The embodiment illustrated shows multiple ball bearings 280 disposed along the rotor interfacing surface 224 of the solid feed guide 212. The rotor interfacing surface 224 may include the top portion 282 and the lower portion 284 with the lower portion 284 nearest the tip 228. Also, as mentioned above, each of the ball bearings 300 bearings may be spring loaded into a concave recess or captured between surfaces 224 and 226. The ball bearings 300 may be disposed in horizontal alignment along the width 286 of the rotor interfacing surface 224 and vertical alignment from the top portion 282 to the lower portion 284 as illustrated. Alternatively, ball bearings 300 may be staggered or randomly distributed along the rotor interfacing surface 224. The diameter 302 of the ball bearings 300 may be uniform or non-uniform from one ball bearing 300 to another. The horizontal spacing 304 and vertical spacing 306 may also be uniform or non-uniform from one ball bearing 300 to another.

In certain embodiments, the multiple discrete contacts 250 may include wheels or rollers having a rotational axis or axle. FIG. 8 illustrates an embodiment of the solid feed guide 212 with rollers 316. The solid feed guide 212 may include a groove 318 running from the top portion 282 of the rotor interfacing surface 224 towards the lower portion 284. The groove 318 may terminate in the lower portion 284 prior to the tip 228. The solid feed guide 212 may include multiple rollers 316 disposed in alignment within the groove 318. Each of the rollers 316 may rotate along an axis 320 (e.g., an axle) in a direction opposite the rotational direction 216 of the rotor 204. For example, each axle 320 may extend through a roller 316 across the groove 318 from one side to another. The rollers 316 provide a curved contact surface in the shape of a cylindrical surface. The diameter of the rollers 316 may vary between embodiments. The spacing between the rollers 316 within the groove 318 may also vary. In addition, the number of rollers in the groove 318 may vary. In some embodiments, the rotor interfacing surface 224 may include multiple grooves 318 for multiple series of rollers 316.

In some embodiments, the movable discrete contacts 250 may not be located directly on the rotor interfacing surface 224 of the solid feed guide 212. FIG. 9 illustrates a side view of the solid feed guide 212 with the movable discrete contact 250 located at an offset away from the surface 224, e.g., behind the solid feed guide 212. Similar to embodiments above, the solid feed guide 212 may include the upper portion 218 and the lower portion 220 that may include the guide wall 222, the rotor interfacing surface 224, and the tip 228. In illustrated embodiment, the solid feed guide 212 includes an extension 330 that extends from a backside 332 of the solid feed guide 212 to the movable discrete contact 250. The movable discrete contact 250 may include a curved contact surface (e.g., a spherical or cylindrical shape) to interface with the outer surface 226 of the rotor 204. For example, the movable discrete contact 250 may include the bearing 260 or roller 316. The bearing 260 may include the ball bearing 300 or the cylindrical bearing 280. In embodiments with the roller 316, the roller 316 may be coupled to the extension 330 via an axle.

As illustrated, the extension 330 may originate from the lower portion 220 of the backside 332 of the solid feed guide 212. In other embodiments, the extension 330 may originate from the upper portion 218 of the solid feed guide 212. The extension 330 may be angled in a radial direction relative to the backside 332 of the solid feed guide 212. For example, the radial angle (i.e., angle between the extension 330 and the backside 332 of solid feed guide 212) may range between about 0 to 90 degrees, 0 to 60 degrees, 30 to 60 degrees, 0 to 45 degrees, 30 to 45 degrees, 0 to 30 degrees, or 0 to 15 degrees. By further example, the radial angle may be about 30, 35, 40, 45, 50, 55, 60 or 65 degrees, or any angle therebetween.

The movable discrete contact 250 located on the backside 332 of the solid feed guide 212 may provide additional support to the solid feed guide 212 to reduce stresses experienced by the lower portion 220 of the solid feed guide 212, particularly the tip 228. Additionally, the backside 332 location of the movable discrete contact 250 may allow a thickness 334 of the solid feed guide 212 to be reduced from a thickness 336 of the standard solid feed guide 212. In certain embodiments, the thickness 334 of the backside supported solid feed guide 212 may be reduced by at least approximately 10, 20, 30, 40, or 50 percent compared to the thickness 336 of the standard solid feed guide 212. For example, the thickness 336 of the standard solid feed guide 212 may be a factor of approximately 1.1 to 3 times greater than the thickness 334 of the backside supported solid feed guide 212. However, the factor may range between approximately 1 to 3, 1 to 2.5, 1 to 2, or 1 to 1.5. The reduced thickness of the solid feed guide 212 may reduce the area requiring a tight tolerance between the rotor interfacing surface 224 and the outer surface 226 of the rotor 204.

In additional embodiments, the movable discrete contacts 250 may be adjustable at the interface between surfaces 224 and 226. FIG. 10 illustrates a cross-sectional side view of the solid feed guide 212 with adjustable movable discrete contacts 250. Like the embodiments above, the solid feed guide 212 may include upper portion 218 and lower portion 220 that may include the guide wall 222, the rotor interfacing surface 224, and tip 228. In addition, the illustrated solid feed guide 212 includes rods 344 extending vertically from the upper portion 218 to the lower portion 220 of the solid feed guide 212. The rods 344 include at one end threaded portions 346 (e.g., male threads) and at the other end movable discrete contacts 250. An adjustment member 348 (e.g., female threads) may engage the threaded portion 346 of the rod 344. The adjustment member 348 may include a nut. The adjustment member 348 enables adjustment of the distance between the movable discrete contacts 250 and the rotor interfacing surface 224, as well as adjustment of the clearance between the contacts 250 and the surface 226. The number of adjustable movable discrete contacts 250 may vary. The adjustable movable discrete contacts 250 may include a curved contact surface (e.g., spherical, cylindrical, semi-spherical, partial cylindrical, etc.) to interface with the outer surface 226 of the rotor 204. The adjustable movable discrete contacts 250 may include the bearing 260 or the roller 316. The bearing 260 may include the ball bearing 300 or the cylindrical bearing 280. The rod 344 may include a spring 350 located towards the end with the discrete contacts 250 to spring load the bearings 260. In embodiments with a roller 316, the roller 316 may be coupled to the rod 344 via an axle.

As mentioned above, a tight tolerance is provided between the solid feed guide 212 and the rotor 204 for efficient operation of the solid feed pump 10. The adjustable movable discrete contacts 250 may help ensure this tight tolerance. The adjustable movable discrete contacts 250 may allow the proper clearance to be obtained between the solid feed guide 212 and the rotor 204 during initial installation. Also, as the movable discrete contacts 250 wear over time, the clearance between the solid feed guide and the rotor may be adjusted to ensure a tight tolerance.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

1. A system, comprising: a solid fuel pump, comprising: a housing; a rotor disposed in the housing; a curved passage disposed between the rotor and the housing; an inlet port coupled to the curved passage; an outlet port coupled to the curved passage; a solid fuel guide extending across the curved passage; and a first roller at an interface between the solid fuel guide and the rotor.
 2. The system of claim 1, wherein the solid fuel guide comprises a guide wall that substantially blocks the curved passage adjacent the inlet port or the outlet port.
 3. The system of claim 1, wherein the solid fuel guide comprises a guide wall extending radially outward from the rotor across the curved passage toward the outlet port.
 4. The system of claim 1, wherein the first roller comprises a wheel coupled to an axle.
 5. The system of claim 1, wherein the first roller comprises a ball disposed in a concave recess.
 6. The system of claim 1, wherein the first roller comprises a cylinder disposed in a concave recess.
 7. The system of claim 1, wherein the first roller is coupled to the solid fuel guide.
 8. The system of claim 1, comprising a second roller offset from the first roller along the interface between the solid fuel guide and the rotor.
 9. The system of claim 8, comprising a third roller offset from the first and second rollers along the interface between the solid fuel guide and the rotor.
 10. A system, comprising: a solid feed pump, comprising: a housing; a rotor disposed in the housing; a curved passage disposed between the rotor and the housing; an inlet port coupled to the curved passage; an outlet port coupled to the curved passage; a solid feed guide extending across the curved passage; and a plurality of discrete contacts distributed along an interface between the solid feed guide and the rotor.
 11. The system of claim 10, wherein each one of the plurality of discrete contacts comprises a curved contact surface.
 12. The system of claim 10, wherein each one of the plurality of discrete contacts comprises a static contact.
 13. The system of claim 10, wherein each one of the plurality of discrete contacts comprises a movable contact.
 14. The system of claim 13, wherein each movable contact comprises a wheel coupled to an axle.
 15. The system of claim 13, wherein each movable contact comprises a ball disposed in a concave recess.
 16. The system of claim 13, wherein each movable contact comprises a cylinder disposed in a concave recess.
 17. The system of claim 10, wherein the plurality of discrete contacts is coupled to the solid feed guide, the solid feed guide comprises a guide wall that blocks the curved passage adjacent the outlet port, and the guide wall extends radially outward from the rotor across the curved passage toward the outlet port.
 18. A system, comprising: a solid feed pump, comprising: a housing; a rotor disposed in the housing; a curved passage disposed between the rotor and the housing; an inlet port coupled to the curved passage; an outlet port coupled to the curved passage; a solid feed guide extending across the curved passage; and a discrete static contact at an interface between the solid feed guide and the rotor.
 19. The system of claim 18, wherein the discrete static contact comprises a curved contact surface.
 20. The system of claim 18, comprising a plurality of discrete static contacts coupled to the solid feed guide along the interface between the solid feed guide and the rotor, wherein the solid feed guide comprises a guide wall that blocks the curved passage adjacent the outlet port, and the guide wall extends radially outward from the rotor across the curved passage toward the outlet port. 